Laniakea Supercluster

The Laniakea Supercluster is a massive structure in the deep universe. It is a galaxy supercluster that contains our own Milky Way. This structure also holds approximately 100,000 other nearby galaxies. Laniakea is one of the largest known cosmic structures in the observable universe. It is considered part of a much larger superstructure. This larger system is known as the Pisces–Cetus Supercluster Complex.

Scientists define Laniakea using the concept of basins of attraction. A basin of attraction is a region where all moving objects flow toward a single point. In this case, most galaxies move toward a central gravitational point. This focal point is called the Great Attractor. The Great Attractor is located near the Norma cluster. Its gravity influences the motion of the Local Group. This group includes our Milky Way galaxy. This movement pattern helps astronomers map the boundaries of the supercluster.

Laniakea is composed of many different parts and sub-structures. It includes the Virgo Supercluster, where the Milky Way resides. It also contains the Hydra–Centaurus Supercluster. Other parts include the Antlia Wall and the Pavo–Indus Supercluster. The Ophiuchus Supercluster is another major component. There are also several bounding voids, such as the Sculptor Void and the Local Void. These voids are empty spaces between the structures. The entire supercluster cocoon contains between 300 and 500 known galaxy clusters and groups.

Astronomers officially defined Laniakea in September 2014. A research team led by R. Brent Tully published these findings. The team included Hélène Courtois, Yehuda Hoffman, and Daniel Pomarède. They used the relative velocities of galaxies to define the supercluster. Before this, astronomers used different definitions for such groups. For example, Tony Fairall suggested in 1988 that some superclusters were connected. He used redshifts to show connections between Virgo and Hydra–Centaurus.

The scale of Laniakea is truly immense. It is stretched out over roughly 500 million light-years. The total mass is approximately 10 to the 23rd power solar masses. This mass is 100,000 times that of the Milky Way. This mass is similar to the Horologium Supercluster. Some galaxy clusters are difficult to detect in this region. They are hidden in the Zone of Avoidance. This area is obscured by gas and dust from our own galaxy.

There is an interesting debate about what a supercluster actually is. Some scientists prefer the traditional definition. This definition describes superclusters as high-density regions of the cosmic web. Because Laniakea is a basin of attraction, some call it a "supercluster cocoon." Others use the term "watershed supercluster." This is because the galaxy motions act like water flowing into a basin. This distinction helps scientists categorize how these massive structures evolve.

Laniakea's future may be different from other superclusters. Most traditional superclusters might collapse in the far future. However, Laniakea is not gravitationally bound. This means its gravity is not strong enough to hold it together forever. Instead, it is projected to be torn apart by dark energy. Recent observations also show Laniakea is moving. It is moving toward the Shapley Concentration. It may even be part of that even larger structure.

The name Laniakea was suggested by Nawaʻa Napoleon. He is an associate professor of Hawaiian language. In Hawaiian, the name means "immense heaven." This name honors the ancient Polynesian navigators. These travelers used the stars to guide them across the Pacific Ocean. Today, we use the stars to find our place in the universe. Laniakea helps us understand our cosmic home.